There have been difficulties when making sintered bodies in the past, in particular sintered bodies for cutting used for providing cutting edges for various machining and cutting purposes. In general, sintered bodies for cutting are made of a cermet or a cemented carbide with a binder phase comprising cobalt. When sintering the body comprising cobalt the cobalt sometimes tends to rise to the surface of the body during the sintering process, creating a surface layer comprising a higher amount of cobalt than further towards the middle of the body for cutting.
It is not desired for all applications to have a higher amount of cobalt at the surface of a body for cutting. The surface cobalt may lower the adhesion abilities for further coating layers, such as CVD layers, added to the surface. Also for cutting bodies not using any further layers, the surface cobalt can be a disadvantage, since chips formed during machining of an object can be welded to the cobalt and thereby cause wear problems. When producing sintered bodies for cutting there is a desire for the sintered bodies to have a surface that has the ability to release the chips from the surface of the sintered bodies. Previously these cutting bodies after sintering have been machined by grinding or by blasting to remove the layer of cobalt.
For other applications the surface cobalt is advantageous, in particular if the cutting surfaces should be welded or brazed to for example saw blades. If the sintering process gives cutting bodies without surface cobalt these bodies needs treatment in order to achieve the desired welding or brazing properties. For this reasons it is highly desirable to be able to control the sintering process in order to either achieve surface cobalt or not achieve surface cobalt.
And thus for further applications it is desirable to be able to control the surface of the same body in order to have cobalt on a predetermined surface and no cobalt on another surface of a body after sintering.